The present invention relates to bookmaking apparatus, and more particularly to an apparatus that prevents a sheet bundle applied with adhesive from remaining inside the apparatus when the apparatus experiences conveyance malfunctions thereby allowing the adhesive to harden. The present invention further relates to a bookmaking apparatus that prevents adhesive applied to the sheet bundle from dripping into and contaminating the machine when bookbinding.
Generally, bookmaking devices are widely used as end devices of image forming apparatus such as printers or copiers, and as apparatus that binds a side of sheets formed with images to a cover sheet after stacking the sheets in page order, forming a bundle, and dispensing adhesive to that side, a variety of systems have been proposed that print predetermined information and at the same time automatically bind sheets, as an on-demand printing system, such as in electronic publication systems. This kind of bookmaking apparatus is used as a device that is separate from an image forming apparatus, and as a stand-alone apparatus that applies adhesive to a side edge (a back side) of printed sheets stacked in a bundle to form a booklet by binding that to a separately conveyed cover sheet. Such bookmaking apparatuses are also used as a system apparatus linked to a discharge outlet of an image forming apparatus to form a booklet by sequentially receiving printed sheets conveyed therefrom.
For example, Japanese Patent Publication No. 2004-209869 discloses a system that automatically finishes a booklet of sheets output from an image forming. Sheets outputted from an image forming apparatus are received from a discharge outlet and are guided to the discharge path and are stacked in a tray provided at a downstream side of the discharge path. The sheet bundle stacked on the tray in a substantially horizontal posture is then turned 90 degrees and guided to an adhesive application apparatus in a vertical posture for the application of adhesive. The above publication further discloses an apparatus that folds a sheet bundle applied with adhesive together with a cover sheet supplied from an inserter provided at a discharge path.
The above publication further discloses a gripping means that applies adhesive to a sheet bundle held in a vertical posture, a container holding adhesive, and a roller arranged in the container. The roller, covered with adhesive, travels along the side edge of the sheets applying adhesive to the bottom edge of the sheets.
In both the stand-alone apparatus and the system apparatus, a thermo-fusion type (hot-melt) adhesive is used. Being in a solid form until it is placed in the container, the adhesive is easy to handle. After it is placed in the container, it melts into a liquid form for application to the sheet bundle. After application, it hardens and becomes fixed to the sheet bundle. The adhesive is selected based upon its ability to harden and become affixed to the sheet bundle after an appropriate amount of time.
Furthermore, in order to prevent sheets from coming loose, the adhesive must harden and become affixed to the sheet bundle after a comparatively short amount of time and that the adhesive is applied without blotches so the sheet bundle and cover sheet are bound together.
Serious problems may occur when sequentially conveyed sheets are collected in a bundle shape, applied with adhesive on an edge thereof, and bound to a cover sheet. In bookmaking systems as disclosed by the above publication, the apparatus stops after dispensing adhesive or while dispensing adhesive while the cover sheet is conveyed to the binding position downstream of the adhesive application position. When the apparatus is stopped, the adhesive may harden and loses its adhesiveness. If a malfunction occurs, such as a paper jam in the process to convey the cover sheet, the apparatus will stop and the cover sheet must be removed and as a result, the sheet bundle that has been applied or is being applied with adhesive may be destroyed. In addition, the apparatus at an upstream side, such as the image forming apparatus must then be reset and the process must be restarted from the image forming stage. This kind of trouble invites complex recovery work, and is recognized as a major detriment to productivity and ease-of-use.
Also, any adhesive applied to the sheet bundle is required to have the proper viscosity to enter between individual sheets of the sheet bundle and not to drip while the sheet itself is conveyed from the image forming apparatus while being exposed to heat. When an image forming apparatus increases its speed to print at high speed the fixing temperature must be increased and the sheet is conveyed while being exposed to high heat levels.
Adhesive applied to the sheet does not harden at a predetermined point and may drip because of the vibrations of the machine. This dripping may cause a problem of adhesive being left in the machine. If the viscosity of adhesive is lowered to minimize the dripping, the pages will not be properly coated and may result in pages falling out. Conversely, if the viscosity is too high, the adhesive will drip and may result in the adhesive sticking to the cover sheet, ruining the esthetic appearance of the booklet. Because it is not possible to control the heat that the sheet itself is exposed to, the dripping of adhesive has been accepted as a necessary evil.
An object of the present invention is to provide a bookmaking apparatus that does not leave a sheet bundle applied with adhesive in the apparatus when conveyance trouble, such as a cover sheet paper jam, occurs; does not leave a cover sheet in the apparatus even if adhesive from a heated sheet bundle drips; and does not soil the cover sheet.
Another object is to provide an image forming system that can continuously perform the covering process without damaging the sheet bundle applied with adhesive even if cover sheet conveyance problems occur.